KR101132250B1 - Process for the preparation of stable polycarbodiimide dispersions in water, which are free of organic solvents and may be used as crosslinking agent - Google Patents

Abstract

A method for preparing stable water soluble polycarbodiimide dispersions containing no organic solvents, which will be used as crosslinking agents, is disclosed. The process comprises: reacting a polyisocyanate in the presence of a carbodiimide catalyst to form a polycarbodiimide, comprising hydrophilic groups and one or more amine and / or hydroxy functional groups during or after polycarbodiimide formation. Terminating the polycarbodiimide chain and / or extending the chain by adding a compound to disperse the resulting compound in water, the pH of which is based on the water and / or the water-soluble dispersion used for the dispersion. And / or between 9 and 14 by addition of buffer. According to the method, terminating or extending the chain with a compound comprising a hydrophilic group and one or more amine functional groups also occurs during or after dispersing the polycarbodiimide in water. Preferred pH of the polycarbodiimide dispersion is between 11 and 13. The present invention also relates to a coating mixture comprising polycarbodiimide dispersions obtained according to the invention as a water soluble resin comprising carboxylic acid functional groups and a crosslinking agent. Finally, the present invention includes a cured material obtained by applying the coating mixture to a substrate and evaporating water.

Description

PROCESS FOR THE PREPARATION OF STABLE POLYCARBODIIMIDE DISPERSIONS IN WATER, WHICH ARE FREE OF ORGANIC SOLVENTS AND MAY BE USED AS CROSSLINKING AGENT}

Polycarbodiimides are known as crosslinkers for water soluble resins containing carboxylic acid functional groups. Most commercially available polycarbodiimide crosslinkers are dissolved in organic solvents, which is disadvantageous for environmental reasons. In addition, the polycarbodiimide crosslinkers must be mixed with water or water and surfactant before they can be mixed with the water soluble resin. In general, such aqueous dispersions are not stable and must be prepared fresh daily. As described in US Pat. No. 56,88875 (= European Patent No. 0686626) and US Pat. No. 5859166, only polycarbodiimides based on water soluble tetramethylxylene diisocyanate are stable in water. However, a disadvantage of such polycarbodiimides is that the conditions for forming carbodiimide from tetramethylxylene diisocyanate are rather extreme: 22 hours at 180 ° C. and 2% of carbodiimide catalyst are required. In addition, polycarbodiimides based on tetramethylxylene diisocyanates are slower and less efficient crosslinkers than isophorone diisocyanate or crosslinkers based on 4,4'-dicyclohexylmethane diisocyanate.

Water-soluble polycarbodiimide dispersions and 4,4′-dicyclohexylmethane obtained from isophorone diisocyanate disclosed in US Pat. No. 5856014, US Pat. No. 5958516, US Pat. No. 6127029, US Pat. No. 6127477. Water soluble polycarbodiimide dispersions obtained from diisocyanates are not stable. Carbodiimide amounts of commercially available water-soluble polycarbodiimide products (Carbodilites from Nisshinbo Industries) were 15-70% of their initial values within 6 weeks in a stability test at 50 ° C. Until reduced.

It is an object of the present invention to provide a method in which the aforementioned disadvantages are eliminated.

DESCRIPTION OF THE INVENTION

According to the present invention there is provided a process for preparing stable water-soluble polycarbodiimide dispersions which do not contain organic solvents, which are to be used as crosslinking agents.

Reacting the polyisocyanate in the presence of a carbodiimide catalyst to form a polycarbodiimide,

Terminating the polycarbodiimide chain and / or extending the chain by addition of a compound comprising a hydrophilic group and one or more amine and / or hydroxy functional groups during or after said polycarbodiimide formation,

Disperse the resulting compound in water,

The pH is characterized in that it is adjusted between 9 and 14 by the addition of a base or a buffer to the water and / or the aqueous dispersion obtained for the dispersion. Alternatively, polycarbodiimide dispersions based on stable water soluble polyisocyanates may be used for capping or chain extension by a compound comprising a hydrophilic group and one or more amine functional groups during or after polycarbodiimide formation. Rather, it is obtained when the polycarbodiimide occurs during or after dispersion in water.

Surprisingly, the stability of the polycarbodiimide dispersions increased significantly at higher pH values and the carbodiimide concentration did not decrease within 8 weeks at 50 ° C. Preferably at the end of the method the pH will be adjusted to a value between 11 and 13.

Existing carbodiimide catalysts described in EP 878496 can be used. Surprisingly, the reaction temperature and reaction time can be reduced when 1-methylphospholene-1-oxide is used as catalyst and for this reason this catalyst is preferred.

The polyisocyanate used to prepare the polycarbodiimide is conventional polyisocyanate and toluene-2,4-diisocyanate, toluene-2,6-diisocyanate and mixtures thereof, diphenylmethane-4,4-diisocyanate , 1,4-phenylene diisocyanate, dicyclohexyl methane-4,4'- diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,6-hexyl diisocyanate, 1, 4-cyclohexyl diisocyanate, norbornyl diisocyanate diisocyanate, or mixtures thereof, preferably dicyclohexyl methane-4,4'- diisocyanate.

Bases used to adjust the pH may be alkali hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, or trialkylamines containing trialkylamines or hydroxyl functions. Optionally, the base or part of the base caps the polycarbodiimide chain with dialkylaminoalkyl-amine or alcohol and / or 0.01-0.3 equivalents of polyol or polyamine to diisocyanate during or after polycarbodiimide formation. It can be included in the polycarbodiimide chain by the addition of a tertiary amine containing.

Buffers can be used to fix the pH. Useful buffers are buffers having an effective pH range between 9 and 14.

Compounds comprising hydrophilic groups and one or more amines and / or hydroxyl groups may be polyethoxy monools or polyethoxy diols, polyethoxy / polypropoxy monools or polyethoxy / polypropoxy diols, polyethoxy Mono amine or polyethoxy diamine, polyethoxy / polypropoxy mono amine or polyethoxy / polypropoxy diamine, diol or diamine with polyalkoxy side chain, hydroxy alkylsulfonate or amine alkylsulfonate or dialkylamino Alkyl alcohol or dialkylaminoalkyl amine.

The polycarbodiimide dispersions of the present invention can be used as a crosslinking agent for resins containing carboxyl groups in a conventional manner: a coating mixture comprising a polycarbodiimide dispersion of the invention and a water soluble resin comprising carboxylic acid functional groups Ready The material is applied to a substrate, for example leather or synthetic leather, and cured by evaporating water. For example, there may be many additional components such as fillers, colorants, pigments, silicones, surfactants and the like.

For several applications it is advantageous if the distance between carbodiimide functional groups in the molecule is increased. In this way, crosslinking will be less rigid, coatings will be more flexible and problems such as graying or brittleness of the coatings, which is the effect of the coating turning gray and matting upon stretching, are prevented. Can be. Thus, flexible segments can be included as "spacers" for separating carbodiimide functional groups in the polycarbodiimide chain. To this end, 0.01-0.30 equivalents of monool or polyol or monoamine or polyamine to polyisocyanate are added during or after polycarbodiimide formation, wherein the polyol or polyamine is for example monohydroxyalkane or polyhydride Oxyalkanes, polyether monools or polyether polyols, polyester polyols, polycarbonate polyols, polycaprolactam polyols, monoaminoalkanes or polyaminoalkanes, polyether monoamines or polyether polyamines.

The polycarbodiimide dispersions of the present invention have several advantages:-the dispersions are stable-the polycarbodiimide is a water soluble dispersion and can be easily mixed with a water soluble resin containing carboxylic acid functionalities-the products are solvent 4,4'-dicyclohexylmethylene diisocyanate (and isophorone diisocyanate), containing no volatile organic vapors released during application and using 1-methylphospholene-1-oxide as a carbodiimide catalyst Carbodiimide formation by is carried out in less extreme conditions than by the diisocyanates described in US Pat. No. 56,888,75 and US Pat. No. 5,859,166.

Example  1A-1F

Preparation of Water-Soluble Dispersions of Polycarbodiimides Based on Dicyclohexylmethane-4,4'-Diisocyanate.

Under a nitrogen atmosphere, 262 g of dicyclohexylmethane-4,4'-diisocyanate (hereinafter referred to as HMDI) and 4 g of 1-methylphospholene-1-oxide are heated to 140 ° C. with stirring and 8.20 isocyanates Heating was continued until the content was obtained. Thereafter, the mixture was cooled to 90-100 ° C. The reaction time was 8 hours. Hydrophilic compounds as indicated in Table 1 were added. When hydroxy functional hydrophilic compounds are used, 0.01 wt% of dibutyl tin laureate is added as a catalyst and the mixtures are added until the NCO-signal disappears in the IR spectrum. It was further reacted at -100 ° C. In Example 1E, an amine functional compound was added after the reaction time of 1 hour. The mixture was cooled to 60-65 ° C. and dispersed in water at 60-65 ° C. while adjusting the amount of solids to 35%. For Example IF, the compound containing the amine functional group was then added to the dispersion and the mixture was stirred for 10 minutes. A 10% aqueous base solution as indicated in Table 1 was added until the pH was 11-12. Stability tests were performed on the samples at 50 ° C. The amount of carbodiimide was checked at two week intervals. The products were stable at 50 ° C. for at least 8 weeks.

a) M-PEG-350 is polyethoxy ethanol with an average molecular weight of 350.

b) DMEA is N-dimethylethanolamine.

c) Na-taurine is sodium 2-aminoethylsulfonate.

Example  2A-2G

Preparation of Water-Soluble Dispersions of Polycarbodiimides Based on HMDI.

The examples of Examples 1A-1F were repeated except that water was replaced with 0.01 M disodium phosphate buffer solution. Stability tests were performed on the samples at 50 ° C. The amount of carbodiimide was checked at two week intervals. The products were stable at 50 ° C. for at least 8 weeks.

Example  3

Preparation of Water Soluble Dispersion of Polycarbodiimide Based on HMDI.

Example 1A was repeated except that 15 g of butanediol was added to the diisocyanate prior to adding the catalyst for carbodiimide formation. The reaction was continued until an isocyanate content of 7.01 was obtained and the amount of M-PEG was 148.61 g.

Example  4

Preparation of Water Soluble Dispersion of Polycarbodiimide Based on HMDI.

Under a nitrogen atmosphere, 262 g of HMDI and 4 g of 1-methylphospholene-1-oxide were heated to 140 ° C. with stirring, heating was continued until an isocyanate content of 14.26 was obtained and the mixture was cooled to 90 ° C. . With 0.01% by weight of dibutyl tin laurate, polyols as shown in Table II were added. Stirring was continued for 30 minutes at 90 ° C. and 147 g of M-PEG-350 were added. Stirring was continued at 90 ° C. until no NCO-signal was observed in the IR spectrum. The mixture was cooled to 60-65 ° C. and dispersed in water at 60-65 ° C. while adjusting the amount of solids to 40%. A 10% NaOH aqueous solution was added until pH was 11. The samples were subjected to the stability test as described above. The products were stable at 50 ° C. for at least 8 weeks.

a) PPG-425 is propylene glycol with an average molecular weight of 425.

Example  5

Preparation of Water-Soluble Dispersions of Polycarbodiimides Based on Diphenylmethane-4,4'-Diisocyanate.

Under a nitrogen atmosphere, 150 g of diphenylmethane-4,4'-diisocyanate and 140 g of M-PEG-350 were heated to 80 ° C and the mixture was stirred at 80 ° C for 60 minutes. 0.4 g of 1-methylphospholene-1-oxide was added and heated, and stirring at 80 ° C. was continued until the NCO-signal disappeared from the IR spectrum. The reaction time was 3 hours. The mixture was cooled to 60-65 ° C. and dispersed in water at 60-65 ° C. while adjusting the amount of solids to 40%. 5% aqueous 1 molal sodium carbonate solution was added and the resulting mixture was stirred until uniform, followed by 10% aqueous sodium hydroxide solution until the pH reached 11-12.

Claims (13)

A process for preparing water-soluble polycarbodiimide dispersions that are stable for at least 8 weeks at 50 ° C. containing no organic solvents, to be used as crosslinking agents: Reacting the polyisocyanate in the presence of a carbodiimide forming catalyst to form a polycarbodiimide, -Terminating the polycarbodiimide chain by adding a compound comprising a hydrophilic group and an amine or hydroxy functional group or a mixture thereof during or after the polycarbodiimide formation, or the driver for forming the polycarbodiimide or A hydrophilic group and then a compound comprising an amine functional group, a hydroxy functional group, an amine and a hydroxy functional group or a mixture thereof is added to extend the polycarbodiimide chain, Disperse the resulting compound in water, Wherein the pH is adjusted between 9 and 14 by addition to the base or buffer or mixtures thereof with water used for the dispersion or the water-soluble dispersion obtained above or both, Wherein the terminating or extending the chain with a compound comprising a hydrophilic group and one or more amine functional groups occurs during or after dispersing the polycarbodiimide in water. Manufacturing method. delete The method of claim 1, Wherein the pH of the polycarbodiimide dispersions is adjusted to a value between 11 and 13, wherein the stable water-soluble polycarbodiimide dispersions. The method of claim 1, The carbodiimide forming catalyst is characterized in that 1-methylphospholene-1-oxide, a process for producing stable water-soluble polycarbodiimide dispersions. The method of claim 1, Polyisocyanates used to prepare the polycarbodiimide include toluene-2,4-diisocyanate, toluene-2,6-diisocyanate and mixtures thereof, diphenylmethane-4,4'-diisocyanate, 1, 4-phenylenediisocyanate, dicyclohexylmethane-4, 4'-diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,6-hexyl diisocyanate, 1,4-cyclo A process for producing stable water-soluble polycarbodiimide dispersions, characterized in that hexyl diisocyanate, norbornyl diisocyanate, or mixtures thereof. The method of claim 1, Wherein said polyisocyanate is dicyclohexylmethane-4,4'-diisocyanate. The method of claim 1, The base is a method of producing stable water-soluble polycarbodiimide dispersions, characterized in that the alkali hydroxide (alkali hydroxyde) is lithium hydroxide, sodium hydroxide, potassium hydroxide, or trialkylamine, or trialkylamine containing hydroxyl functional groups. . The method of claim 1, The base caps the polycarbodiimide chain with dialkylaminoalkylamine or dialkylaminoalkylalcohol, or 0.01-0.3 equivalents of polyol or polyamine to diisocyanate during or after polycarbodiimide formation. Method for producing a stable water-soluble polycarbodiimide dispersion, characterized in that bonded to the polycarbodiimide chain by adding a tertiary amine comprising a. The method of claim 1, The pH range in which the buffer is activated is between 9 and 14, the method of producing a stable water-soluble polycarbodiimide dispersions. The method of claim 1, Compounds comprising such hydrophilic groups, and one or more amine or hydroxyl functional groups or mixtures thereof may be polyethoxy monools or polyethoxy diols, polyethoxy / polypropoxy monools or polyethoxy / polyprop Foxy diols, polyethoxy monoamines or polyethoxy diamines, polyethoxy / polypropoxy monoamines or polyethoxy / polypropoxy diamines, diols or diamines with polyalkoxy side chains, hydroxy alkylsulfonates or amine alkyls A sulfonate, or a dialkylaminoalkyl alcohol or a dialkylaminoalkyl amine or a mixture thereof, a process for producing stable water-soluble polycarbodiimide dispersions. The method of claim 1, Before or during the formation of the polycarbodiimide, 0.01-0.30 equivalents of monool or polyol or monoamine or polyamine are added to the polyisocyanate, the polyol or polyamine being polyhydroxy-alkane, polyether polyol, A process for producing stable water-soluble polycarbodiimide dispersions, characterized in that it is selected from polyester polyols, polycarbonate polyols, polycaprolactam polyols, polyamino-alkanes and polyether polyamines. As a water-soluble resin and a crosslinking agent comprising carboxylic acid functional groups, the compound according to claim 1, 3, 4, 5, 6, 7, 8, 9, 10 and 11. Coating mixture comprising polycarbodiimide dispersions obtained according to any one of the preceding claims. A cured material obtained by applying the coating mixture of claim 12 to a substrate and evaporating water.